Allocated fixed costs, often called common costs, are costs that are not traceable to a particular product, service, product line, or segment. They are never relevant because the costs are assigned to a number of products.llocated fixed costs, often called common costs, are costs that are not traceable to a particular product, service, product line, or segment. They are never relevant because the costs are assigned to a number of products.
Definition of roost. 1  1a : a support on which birds restb : a place where winged animals and especially birds customarily roost. 2  2 : a group of birds roosting together.
v. 1  Birds to land on or rest upon a perch:[no object]The birds perched on the telephone wires. 2  to (cause to) settle or rest in some high position, as if on a perch: [~ + object]He was perched on his throne.[no object]The prince perched on his throne.